These robots serve as mobile landmines for the Chinese army. Their method of attack is to approach enemy targets and explode. They are only encountered briefly during the quest "Paving the Way" and thus, there is very little information to be gathered on them.
A Chinese terminal entry advises their own soldiers to be careful around the drones, even though they are configured to only attack Americans. Additionally, you will occasionally see a Chinese soldier fighting one of these on the way to the Chimera Armor Depot, suggesting that the prototypes might still suffer from problems with its combat inhibitor, or might even lack one entirely.
They will explode upon death, killing any other spider drones nearby, and inflicting damage to anything in close vicinity.
Targeting the spider drones at any distance greater than a few feet with V.A.T.S. may prove difficult, as the drones are very small targets and thus a lower chance to hit ranging from 0% at more than 20 feet to about 50% at about 5 feet.
The body of the drone is the unused model of the cryo mine.
When traveling with a 3-man fire team, the team will generally destroy the mines before they can get close enough to harm the player.